夹具质量对标准测力仪的影响

分析了用试验机进行力学性能检定过程中，夹具的质量对标准测力仪造成的影响，并通过分析原因，给出消除或减小这种影响的方法。     

一种激光长刻机的工作原理

介绍了一种静态激光长刻机的工作原理,并介绍了该光刻方法的关键技术和工艺.     

Developing a dust storm detection method combining Support Vector Machine and satellite data in typical dust regions of Asia

Enhancing the dust storm detection is a key part for the environmental protection, human healthy and economic development. The goal of this paper is to propose a new Support Vector Machine (SVM)-based method to automatically detect dust storms using remote sensing data. Existing methods dealing with this problem are usually threshold-based that are of great complexity and uncertainty. In this paper we propose a simple and reliable method combining SVM with MODIS L1 data and explore the optimal band combinations used as the feature vectors of SVM. The developed method was evaluated by MODIS and OMI data qualitatively and quantitatively on three study sites located in the Arabian Desert, Gobi Desert and Taklimakan Desert, and it was also compared to three other traditional methods based on their accuracy, complexity, reliability and sensitivity to thresholds. The detection results demonstrated that the combination of (Band7 − Band3)/(Band7 + Band3) ((B7 − B3)/(B7 + B3)), Band20 − Band31 (B20 − B31), and Band31/Band32 (B31/B32) can detect the dust storms more precisely than other individual bands or their combination. The comparison among those cases indicated that the proposed automatic method exhibited an advantage of minimizing the uncertainty and complexity, which were the limits of defining thresholds based on the threshold-based methods. The conclusions can provide references for studies that focus on statistical-based dust storm detection.     

Impact of local and global factors and meteorological parameters in temporal variation of atmospheric potential gradient

In this research work, we have performed comparative diurnal variations of atmospheric Potential Gradient (PG) of fair-weather days by using the data of three stations installed in Northern, Pakistan for the year 2018. We investigated the impact of both local and global factors and meteorological parameters in the diurnal variation of atmospheric Potential Gradient on the annual and seasonal time scale. We observed two peaks, primary and secondary. This is because of the land-based measurements of annual and seasonal variations. The annual average curve of Potential Gradient of all three stations: Islamabad (CES), Muzaffarabad (MZF), and Balakot (BKT) demonstrated a notable deviation from the standard oceanic Carnegie curve. The atmospheric Potential Gradient variations are due to numerous meteorological factors e.g., air pollution, humidity, aerosol particles, fog, and temperature. Among three stations, the MZF station is located in highland (mountainous) and it demonstrated a higher atmospheric Potential Gradient. We further differentiate the results of our three stations with global results for authenticity and observed coherence between them. In addition, a positive correlation of fair-weather Potential Gradient is observed with temperature and a notable correlation between relative humidity and atmospheric Potential Gradient for all the three observatories.     

空间引力波探测微牛电推进寿命评估研究现状

阐述了空间引力波探测任务中无拖曳控制技术对推进系统的特殊要求，介绍了目前主要的备选推进类型：冷气推进、离子电推进、会切型霍尔电推进、胶体电推进。针对面向空间引力波探测任务的电推进系统的寿命评估工作进行了任务分析，报告了目前微牛级电推进系统寿命试验研究现状，举例说明了目前主要应用的电推进装置寿命预测方式，包括半经验模型预测、数值模拟预测、基于数据驱动的预测以及系统层面的可靠性评估方法。对目前微牛级电推进系统的寿命评估研究现状进行总结，给出了发展思路。     

The future role of relay satellites for orbital telerobotics

Orbital robotics focuses on a variety of applications, as e.g. inspection and repair activities, spacecraft construction or orbit corrections. On-Orbit Servicing (OOS) activities have to be closely monitored by operators on ground. A direct contact to the spacecraft in Low Earth Orbit (LEO) is limiting the operational time of the robotic application. Therefore, geostationary satellites are desirable to relay the OOS signals and extend the servicing time window. A geostationary satellite in the communication chain not only introduces additional boundary conditions to the mission but also increases the time delay in the system. The latter is not very critical if the servicer satellite is operating autonomously. However, if the servicer is operating in a supervised control regime with a human in the loop, the increased time delay will have an impact on the operator’s task performance.     

影响聚四氟乙烯材料加工表面粗糙度因素的研究

在现代航空发动机的产品中,保护圈、密封件等零件广泛使用聚四氟乙烯材料制造.在加工中多采用车削加工,粗糙度一般为Ra1.6,本文通过选用不同车床、刀具、加工参数的方法,提高该类材料加工后的表面粗糙度,为后续加工提供经验和数据.     

Improving orbit prediction accuracy through supervised machine learning

Due to the lack of information such as the space environment condition and resident space objects’ (RSOs’) body characteristics, current orbit predictions that are solely grounded on physics-based models may fail to achieve required accuracy for collision avoidance and have led to satellite collisions already. This paper presents a methodology to predict RSOs’ trajectories with higher accuracy than that of the current methods. Inspired by the machine learning (ML) theory through which the models are learned based on large amounts of observed data and the prediction is conducted without explicitly modeling space objects and space environment, the proposed ML approach integrates physics-based orbit prediction algorithms with a learning-based process that focuses on reducing the prediction errors. Using a simulation-based space catalog environment as the test bed, the paper demonstrates three types of generalization capability for the proposed ML approach: (1) the ML model can be used to improve the same RSO’s orbit information that is not available during the learning process but shares the same time interval as the training data; (2) the ML model can be used to improve predictions of the same RSO at future epochs; and (3) the ML model based on a RSO can be applied to other RSOs that share some common features.     

纺纱机微电脑控制仪的设计及实现

单片机由于具有功能强，性能价格比高，使用方便等优点，已在工业测试和控制中得到了日益广泛的应用。本文介绍了采用单片机对纺纱机纺纱工艺过程进行自动控制，控制仪的硬件结构、软件设计及抗干扰措施。     

基于双幂次趋近律的终端滑模舵机控制器设计

针对电动舵机系统的快响应鲁棒控制问题,提出了一种基于双幂次趋近律的全局非奇异终端滑模控制方法.首先,建立了舵机系统的数学模型,将气动干扰和摩擦建模为有界扰动;其次,根据系统模型构建非奇异终端滑模面,结合双幂次趋近律设计舵机控制器,从而保证滑模面的固定时间可达性,充分利用滑模控制方法的鲁棒性和不变性,并提高舵机系统的响应...